Bijan Mohammadi

Delaunay mesh generation governed by metric specifications. Part II. applications

Abstract This paper gives some application examples resulting from a governed Delaunay type mesh generation method. Isotropic and anisotropic cases are considered, these specifications being given via a metric map. The paper illustrates a study whose algorithmical aspects are described in a report referred to as part 1. Academic examples as well as examples in CFD are discussed.

A NEW OPTIMAL SHAPE DESIGN PROCEDURE FOR INVISCID AND VISCOUS TURBULENT FLOWS

A new approach for optimal shape design is introduced. The main ingredients are an unstructured CAD-free framework for geometry deformation and automatic differentiation (AD) in reverse mode. Transonic inviscid and viscous turbulent flows are investigated. Both two- and three-dimensional configurations are considered. These cases involve up to several thousand control parameters.

Rough boundaries and wall laws

SUMMARY We describe a new approach for developing new wall-laws for rough surfaces. We also give error estimates on a simple model. # 1998 John Wiley & Sons, Ltd. Int. J. Numer. Meth. Fluids, 27: 169‐177 (1998)

Mesh adaption and automatic differentiation in a CAD-free framework for optimal shape design

A new approach for optimal shape design based on a CAD-free framework for shape and unstructured mesh deformations, automatic differentiation for the gradient computation and mesh adaption by metric control in 2D is presented. The CAD-free framework is shown to be particularly convenient for optimization when the mesh connectivities and control space size are variable during optimization. Constrained optimization for a transonic regime has been investigated in both 2D and 3D

Unsteady separated turbulent flows computation with wall-laws and k - ε model

Abstract This paper is devoted to the description of our experience in unsteady and separated flows simulations with the classical κ — e model and wall-laws. The wall-laws we use are original and take into account pressure and convection effects and are valid up to the wall.

A Critical Evaluation of the Classical k-ε Model and Wall-Laws for Unsteady Flows Over Bluflf Bodies

The classical k-e model and a new implementation of wall-laws have been evaluated for unsteady turbulent flows past square and circular cylinders. We show that good numerics can lead to a serious improvement of the results. In the case of the flow past a square cylinder (Lyns test case), results agree surprisingly well with the experimental data. In the analysis of the vortex shedding flow past a circular cylinder also the agreement is quite good for the sub-critical regime but not entirely satisfactory after the critical Reynolds number (i.e., the drag crisis phenomenon).

Mesh Adaption and Automatic Differentiation for Optimal Shape Design

Abstract A new approach for optimal shape design based on a CAD-free framework for shape and unstructured mesh deformations, automatic differentiation for the gradient computation and mesh adaption by metric control is presented. The CAD-free framework is shown to be particularly convenient for optimization when the mesh connectivities and control space size are variable during optimization. Constrained optimizations for subsonic, transonic and supersonic regimes have been investigated.

Simulation of turbulence with the k-ϵ model

Abstract The k - ϵ model is investigated for the simulation of turbulence for compressible and incompressible flows. We study it from the point of view of the numerical analyst (positivity of k and ϵ , boundedness, …). A robust numerical implementation is proposed and several numerical examples are given.

Anisotropic mesh adaptation. Applications to transient CFD problems

The classical adaptation scheme appears inappropriate when dealing with transient fluid problems. Hence, we propose a new adaptation scheme, based on the resolution of a transient fixed point problem for the couple mesh-solution as well as a metric intersection in time. The computational metric is provided by an anisotropic (geometrical) error estimate. An example is given to show the efficiency of the proposed approach.

Platform for Multi-Model Design

This paper introduces a global platform for the simulation and the design of multi-model configurations. Fluid-structure interaction and optimization procedures are coupled with turbulent incompressible and compressible flow solvers in order to treat complex aerodynamics problems.First, the equations used in modeling the fluid and the structure are presented, as well as the numerics used in the solvers. Then follows the description of our optimization framework, the gradient approximation and several optimization methods we employed.The applications concern shape optimization for turbomachinery blades and aircraft airfoils and shape optimization coupled with aeroelasticity in aeronautics. The platform is dedicated to the treatment of realistic problems and serves as a powerful tool for design in industrial environments.